The present invention relates to a magnetic recording system using a double-layered perpendicular magnetic recording medium, and a magnetic head mounted in the magnetic recording system.
In order to promote higher recording density of a hard-disk drive, it is considered advantageous to adopt a double-layered perpendicular magnetic recording method using a double-layered perpendicular magnetic recording medium having a soft magnetic underlying layer, as a magnetic recording medium, and using a single-pole type write head (hereinafter referred to as an SPT head) having a main pole and return pole, as a magnetic write head.
It has since been validated that with a magnetic recording system, an external magnetic field inadvertently applied from outside a housing thereof, and presence of a floating magnetic field present inside the magnetic recording system result in degradation of magnetized information as recorded, thereby causing a serious problem in applications thereof. In particular, in the case of the double-layered perpendicular magnetic recording system, the use of a double-layered medium acts such that the soft magnetic underlying layer thereof pulls in the external magnetic field, and a magnetic field produced by convergence of magnetic fluxes, due to interaction between the double-layered medium and a magnetic head, causes erasure of magnetization already recorded, so that there is a good possibility of information being lost, thereby creating a cause for deterioration in reliability of the magnetic recording system. There exists documentation concerning problems that recorded information is lost by the agency of the external magnetic field; however, no documentation is concerned with the case where a magnetic field in a direction perpendicular to a medium plane is applied, centering on the erasure of recorded magnetization, by the agency of the main pole of the SPT head. A known system is shown in JP-A No. 185672/2004.